Several types of electric vaporizers are known in the prior art for vaporizing insect repellers from tablets. These vaporizers usually operate at temperatures of 120.degree. C. (measured at the contact area of the tablet and healing element). Such temperature was found to be too high for use for vaporizing air freshener tablets, which at such temperature may either decompose, or vaporize instantaneously thus loosing the long term slow release effect. Such as the system described in EP 104758 (by Spector D).
Several vaporizers were tried in the prior art to overcome this draw back. The best known is a Japanese version, which introduced the tablet contact area at a position distanced from the heating element, the tablet contact plate was placed at a position below the heating element and thus the vaporized air freshener vapor was released at a lower rate.
The major disadvantages of this system is the fact that only one tablet can be used at the time. The other disadvantage is that the vaporized air freshener rises through the device whereby some of the vapor may come into contact with the heating element at a temperature much above the desired one, resulting possible decomposition of the vapor; and other parts of the vapor may condense on the cooler parts of the device.
Another system describes a double tablet canister placed on both sides of a heating element as described in DE3701499 by Global-Werk. This device has a disadvantage of having both tablets exposed to the high temperature of the heating element.